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    <title>Document</title>
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<body>
    <script>
        // 测试题一
        var A = function(){

        }
        A.prototype.n = 1
        var b = new A()
        A.prototype = {
            n:2,
            m:3
        }
        var c = new A()
        console.log(b.n,b.m,c.n,c.m);   //1 undefined 2 3

        // 测试题二
        var F = function(){}
        Object.prototype.a = function(){
            console.log('a()');
        }
        Function.prototype.b = function(){
            console.log('b()');
        }
        var f = new F()
        f.a()     //a()
        // f.b()  //找不到报错
        F.a()     //a()
        F.b()     //b()
        
    </script>
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